Messages in this thread | | | Date | Mon, 3 Jul 2023 16:36:43 +0200 | From | Jan Kara <> | Subject | Re: fs/namei.c:4875 vfs_rename() warn: variable dereferenced before check 'source' (see line 4830) |
| |
On Mon 03-07-23 15:16:36, Dan Carpenter wrote: > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > head: 995b406c7e972fab181a4bb57f3b95e59b8e5bf3 > commit: 28eceeda130f5058074dd007d9c59d2e8bc5af2e fs: Lock moved directories > config: x86_64-randconfig-m001-20230702 (https://download.01.org/0day-ci/archive/20230703/202307030026.9sE2pk2x-lkp@intel.com/config) > compiler: gcc-12 (Debian 12.2.0-14) 12.2.0 > reproduce: (https://download.01.org/0day-ci/archive/20230703/202307030026.9sE2pk2x-lkp@intel.com/reproduce) > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot <lkp@intel.com> > | Reported-by: Dan Carpenter <dan.carpenter@linaro.org> > | Closes: https://lore.kernel.org/r/202307030026.9sE2pk2x-lkp@intel.com/ > > New smatch warnings: > fs/namei.c:4875 vfs_rename() warn: variable dereferenced before check 'source' (see line 4830)
Yeah, the check for source being non-NULL in:
if (source) inode_unlock(source);
is pointless. When we are renaming something, we are guaranteed "something" exists ;). I'll send a cleanup patch.
Honza
> > vim +/source +4875 fs/namei.c > > 9fe61450972d39 Christian Brauner 2021-01-21 4752 int vfs_rename(struct renamedata *rd) > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4753 { > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4754 int error; > 9fe61450972d39 Christian Brauner 2021-01-21 4755 struct inode *old_dir = rd->old_dir, *new_dir = rd->new_dir; > 9fe61450972d39 Christian Brauner 2021-01-21 4756 struct dentry *old_dentry = rd->old_dentry; > 9fe61450972d39 Christian Brauner 2021-01-21 4757 struct dentry *new_dentry = rd->new_dentry; > 9fe61450972d39 Christian Brauner 2021-01-21 4758 struct inode **delegated_inode = rd->delegated_inode; > 9fe61450972d39 Christian Brauner 2021-01-21 4759 unsigned int flags = rd->flags; > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4760 bool is_dir = d_is_dir(old_dentry); > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4761 struct inode *source = old_dentry->d_inode; > 9055cba711891a Sage Weil 2011-05-24 4762 struct inode *target = new_dentry->d_inode; > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4763 bool new_is_dir = false; > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4764 unsigned max_links = new_dir->i_sb->s_max_links; > 49d31c2f389acf Al Viro 2017-07-07 4765 struct name_snapshot old_name; > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4766 > 8d3e2936375bac Miklos Szeredi 2016-12-16 4767 if (source == target) > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4768 return 0; > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4769 > 4609e1f18e19c3 Christian Brauner 2023-01-13 4770 error = may_delete(rd->old_mnt_idmap, old_dir, old_dentry, is_dir); > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4771 if (error) > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4772 return error; > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4773 > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4774 if (!target) { > 4609e1f18e19c3 Christian Brauner 2023-01-13 4775 error = may_create(rd->new_mnt_idmap, new_dir, new_dentry); > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4776 } else { > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4777 new_is_dir = d_is_dir(new_dentry); > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4778 > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4779 if (!(flags & RENAME_EXCHANGE)) > 4609e1f18e19c3 Christian Brauner 2023-01-13 4780 error = may_delete(rd->new_mnt_idmap, new_dir, > 6521f891708292 Christian Brauner 2021-01-21 4781 new_dentry, is_dir); > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4782 else > 4609e1f18e19c3 Christian Brauner 2023-01-13 4783 error = may_delete(rd->new_mnt_idmap, new_dir, > 6521f891708292 Christian Brauner 2021-01-21 4784 new_dentry, new_is_dir); > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4785 } > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4786 if (error) > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4787 return error; > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4788 > 2773bf00aeb9bf Miklos Szeredi 2016-09-27 4789 if (!old_dir->i_op->rename) > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4790 return -EPERM; > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4791 > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4792 /* > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4793 * If we are going to change the parent - check write permissions, > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4794 * we'll need to flip '..'. > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4795 */ > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4796 if (new_dir != old_dir) { > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4797 if (is_dir) { > 4609e1f18e19c3 Christian Brauner 2023-01-13 4798 error = inode_permission(rd->old_mnt_idmap, source, > 47291baa8ddfda Christian Brauner 2021-01-21 4799 MAY_WRITE); > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4800 if (error) > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4801 return error; > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4802 } > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4803 if ((flags & RENAME_EXCHANGE) && new_is_dir) { > 4609e1f18e19c3 Christian Brauner 2023-01-13 4804 error = inode_permission(rd->new_mnt_idmap, target, > 47291baa8ddfda Christian Brauner 2021-01-21 4805 MAY_WRITE); > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4806 if (error) > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4807 return error; > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4808 } > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4809 } > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4810 > 0b3974eb04c487 Miklos Szeredi 2014-04-01 4811 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, > 0b3974eb04c487 Miklos Szeredi 2014-04-01 4812 flags); > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4813 if (error) > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4814 return error; > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4815 > 49d31c2f389acf Al Viro 2017-07-07 4816 take_dentry_name_snapshot(&old_name, old_dentry); > 1d2ef590148300 Al Viro 2011-09-14 4817 dget(new_dentry); > 28eceeda130f50 Jan Kara 2023-06-01 4818 /* > 28eceeda130f50 Jan Kara 2023-06-01 4819 * Lock all moved children. Moved directories may need to change parent > 28eceeda130f50 Jan Kara 2023-06-01 4820 * pointer so they need the lock to prevent against concurrent > 28eceeda130f50 Jan Kara 2023-06-01 4821 * directory changes moving parent pointer. For regular files we've > 28eceeda130f50 Jan Kara 2023-06-01 4822 * historically always done this. The lockdep locking subclasses are > 28eceeda130f50 Jan Kara 2023-06-01 4823 * somewhat arbitrary but RENAME_EXCHANGE in particular can swap > 28eceeda130f50 Jan Kara 2023-06-01 4824 * regular files and directories so it's difficult to tell which > 28eceeda130f50 Jan Kara 2023-06-01 4825 * subclasses to use. > 28eceeda130f50 Jan Kara 2023-06-01 4826 */ > 28eceeda130f50 Jan Kara 2023-06-01 4827 lock_two_inodes(source, target, I_MUTEX_NORMAL, I_MUTEX_NONDIR2); > 9055cba711891a Sage Weil 2011-05-24 4828 > 51cc3a6620a6ca Hugh Dickins 2021-09-02 4829 error = -EPERM; > 51cc3a6620a6ca Hugh Dickins 2021-09-02 @4830 if (IS_SWAPFILE(source) || (target && IS_SWAPFILE(target))) > ^^^^^^ > Dereferenced. > > 51cc3a6620a6ca Hugh Dickins 2021-09-02 4831 goto out; > ^^^^^^^^ > 51cc3a6620a6ca Hugh Dickins 2021-09-02 4832 > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4833 error = -EBUSY; > 7af1364ffa64db Eric W. Biederman 2013-10-04 4834 if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) > 9055cba711891a Sage Weil 2011-05-24 4835 goto out; > 9055cba711891a Sage Weil 2011-05-24 4836 > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4837 if (max_links && new_dir != old_dir) { > 8de52778798fe3 Al Viro 2012-02-06 4838 error = -EMLINK; > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4839 if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) > 8de52778798fe3 Al Viro 2012-02-06 4840 goto out; > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4841 if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4842 old_dir->i_nlink >= max_links) > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4843 goto out; > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4844 } > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4845 if (!is_dir) { > 8e6d782cab5088 J. Bruce Fields 2011-09-20 4846 error = try_break_deleg(source, delegated_inode); > 8e6d782cab5088 J. Bruce Fields 2011-09-20 4847 if (error) > 8e6d782cab5088 J. Bruce Fields 2011-09-20 4848 goto out; > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4849 } > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4850 if (target && !new_is_dir) { > 8e6d782cab5088 J. Bruce Fields 2011-09-20 4851 error = try_break_deleg(target, delegated_inode); > 8e6d782cab5088 J. Bruce Fields 2011-09-20 4852 if (error) > 8e6d782cab5088 J. Bruce Fields 2011-09-20 4853 goto out; > 8e6d782cab5088 J. Bruce Fields 2011-09-20 4854 } > e18275ae55e07a Christian Brauner 2023-01-13 4855 error = old_dir->i_op->rename(rd->new_mnt_idmap, old_dir, old_dentry, > 520c8b16505236 Miklos Szeredi 2014-04-01 4856 new_dir, new_dentry, flags); > 51892bbb57e878 Sage Weil 2011-05-24 4857 if (error) > 51892bbb57e878 Sage Weil 2011-05-24 4858 goto out; > 51892bbb57e878 Sage Weil 2011-05-24 4859 > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4860 if (!(flags & RENAME_EXCHANGE) && target) { > 8767712f26d18a Al Viro 2018-05-27 4861 if (is_dir) { > 8767712f26d18a Al Viro 2018-05-27 4862 shrink_dcache_parent(new_dentry); > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4863 target->i_flags |= S_DEAD; > 8767712f26d18a Al Viro 2018-05-27 4864 } > d83c49f3e36cec Al Viro 2010-04-30 4865 dont_mount(new_dentry); > 8ed936b5671bfb Eric W. Biederman 2013-10-01 4866 detach_mounts(new_dentry); > bc27027a73e8b8 Miklos Szeredi 2014-04-01 4867 } > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4868 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4869 if (!(flags & RENAME_EXCHANGE)) > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4870 d_move(old_dentry, new_dentry); > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4871 else > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4872 d_exchange(old_dentry, new_dentry); > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4873 } > 51892bbb57e878 Sage Weil 2011-05-24 4874 out: > 28eceeda130f50 Jan Kara 2023-06-01 @4875 if (source) > ^^^^^^ > This check could be removed. > > 28eceeda130f50 Jan Kara 2023-06-01 4876 inode_unlock(source); > 28eceeda130f50 Jan Kara 2023-06-01 4877 if (target) > 5955102c9984fa Al Viro 2016-01-22 4878 inode_unlock(target); > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4879 dput(new_dentry); > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4880 if (!error) { > f4ec3a3d43bcdc Al Viro 2019-04-26 4881 fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4882 !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4883 if (flags & RENAME_EXCHANGE) { > f4ec3a3d43bcdc Al Viro 2019-04-26 4884 fsnotify_move(new_dir, old_dir, &old_dentry->d_name, > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4885 new_is_dir, NULL, new_dentry); > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4886 } > da1ce0670c14d8 Miklos Szeredi 2014-04-01 4887 } > 49d31c2f389acf Al Viro 2017-07-07 4888 release_dentry_name_snapshot(&old_name); > 0eeca28300df11 Robert Love 2005-07-12 4889 > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4890 return error; > ^1da177e4c3f41 Linus Torvalds 2005-04-16 4891 } > > -- > 0-DAY CI Kernel Test Service > https://github.com/intel/lkp-tests/wiki > -- Jan Kara <jack@suse.com> SUSE Labs, CR
| |